Sediment DNA reveals 300,000-year timeline of ancient and modern humans living in Siberia

Denisova Cave is located in the foothills of the Altai Mountains in southern Siberia. It is the only site in the world known to have been inhabited by Denisovans and their relatives, Neanderthals.neanderthal man) – Which sometimes overlapping – as well as by some of the oldest modern humans (sane man) to spread in North Asia.

Our New study The history of this site over the past 300,000 years gathers from fragments of ancient DNA that have survived in the sediments of the caves. Our findings reveal multiple transformations of ancient and modern humans during this period, as well as major changes in the diversity of other animals.

We discovered that Denisovans were among the first tool makers at the site, while Neanderthals were the only human occupants about 130,000 to 80,000 years ago. The first modern humans arrived much later, just as the last Denisovans and Neanderthals were leaving the scene.

We also detected remarkable changes in human and animal DNA species around 200,000 and 100,000 years ago, coinciding with major shifts in climatic and environmental conditions.

hereditary ghosts

Excavations by our Russian colleagues in the cave have revealed about ten fossils of Denisovans and Neanderthals over the past 40 years, but none of those of modern humans have been found.

Instead, the presence of modern humans in the cave was predicted based on the restoration of artefacts made of stone, animal bones, teeth, mammoth ivory, ostrich eggshells, marble and precious stones.

The paucity of excavations at the site also means that questions remain about when different groups of humans occupied the cave, and which of them were responsible for making certain artifacts.

We were able to put meat on lost bones using genetic traces of ancient humans and many other mammals preserved in cave deposits. And we did that without having to find any more fossils.

Our latest work is the most comprehensive study to date of ancient DNA extracted from sediments at any one site in the world. It builds on Pioneering Research Published in 2017.

We extracted mitochondrial DNA from more than 700 samples and fixed it in a timetable Denisova Cave, creating a detailed picture of the humans and animals that were present at this famous site at various times in the past.

Troubled times

We retrieved ancient human DNA from 175 sediment samples – more than ten times the number of human fossils found at the site. Several interesting results emerged from our genetic analyzes.

We found that Denisovans were present in the cave, both inside and outside the cave, from 250,000 years ago to 60,000 years ago. And they were the only humans at the site between 250,000 and 200,000 years ago, so we can now say with more confidence that they likely produced stone tools recovered from these layers.

Denisovan fossils and ancient DNA found in only one Another site, on the edge of the Tibetan plateau.

Meanwhile, Neanderthals first appeared in Denisova Cave about 200,000 years ago, with a previously unknown assortment of DNA. They disappeared from the site about 40 thousand years ago, around the same time Neanderthals disappeared in other parts of Eurasia.

Importantly, we were only able to find traces of Neanderthal DNA in sediments dating between 130,000 and 80,000 years ago at Denisova Cave – and none of the Denisovans.

This time interval coincides with a major change in the Earth’s climate: the beginning of the last Ice Age. This was a relatively warm period similar to the present. It was a shift from one type of Denisovan DNA 130,000 years ago to another 80,000 years ago.

This is consistent with previous results from genetic analysis of Denisovan fossils, which indicated a possible turnover in the Denisovan population. It also coincides with the replacement of the population Neanderthals in Spain About 100,000 years ago – it was recognized again from ancient DNA in cave deposits.

We have also recovered ancient DNA of modern humans from sediments deposited in Denisova Cave during the past 60,000 years. No recent human fossils have been found at the site, so these DNA traces – from the same layers of jewelry and pendants made of stone, bone, teeth and ivory – are the first direct evidence of sane manin the cave.

Denisova Zoo

We recovered DNA from other ancient animals from 94% of the sediment samples. This provides new avenues for the use of caves by more than a dozen taxonomic families of mammals, including species such as bear, hyena, wolf and woolly mammoth.

Previous studies They showed that the cave was sometimes occupied by hyenas and bears. Our findings take this even further, revealing that cave bears dominated between 300,000 and 200,000 years ago, after which brown bears became more abundant.

We also identified two major shifts in hyena species present at different times, with fluctuations occurring when climatic conditions changed from relatively warm to cold 200,000 years ago, and from relatively cold to warm 100,000 years ago.

The timing of these shifts, along with the patterns we detected for Denisovans and Neanderthals, suggest that these events were most likely related to environmental changes.

sediment diary

The strength of sediment DNA lies in the fact that sediments are ubiquitous in archaeological and paleontological sites. Even small samples can contain genetic traces of a variety of animals – including humans – in the absence of fossils.

Sediments often also contain plant remains and other materials that can be used to reconstruct ancient environments, while obtaining timelines. Live Dating sediment granules.

By sampling sites with high sediment DNA density, the tides and flows of humans and other animals can be compared to records of past environmental change. Making these crucial connections can help shed light on the dark corners of our planet’s history.

Elena Zavala, PhD student, Max Planck Institute for Evolutionary Anthropology; Matthias MeyerGroup Leader, Advanced DNA Sequencing Technologies Group, Max Planck Institute for Evolutionary Anthropology; Richard Burt Roberts, director of the ARC Center of Excellence for Australian Biodiversity and Heritage (CABAH), University of Wollongong, And the Zenobia JacobsProfessor University of Wollongong

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